The intend to study the neuronal circadian oscillator system in the eye of Aplysia (an opisthobranch mollusk) as a model system in hope of how a slow (approximately 24-hours) process is generated in the nervous system and how it controls behavior. This innate neural circadian process in the eye is normally entrainable by light-dark cycles in the environment but will free-run as a totally isolated organ system in vitro in continuous darkness for periods up to 2 weeks. Under such conditions, the frequency of compound action pooentials in the optic nerve follows a circardian rhythm (CR). Evidence from this laboratory indicates that the eyes are the dominant circadian oscillator system driving or regulating circadian locomotor behavior in intact Aplysia. We will use a variety of quantitative methods and approaches in this study: on-line TV camera-video encoder-computer determinations of locomotor velocity as a function of time, continuously, over weeks, effects of sectioning the optic nerves, the pleurovisceral connective and other surgical lesions of neural structures on circadian locomotion; biochemical characterization of eye compounds, particularly peptides, which affect circadian locomotion; electrophysiological, morphological (light- and electron-microscopic), and biochemical investigation of the eye, including intracellular recording and dye-marking with lucifer yellow and horseradish peroxidase to determine the nature of the neurons and cells involved in the circadian process. Radioactive 2-deoxyglucose (2DG) labeling will be used to determine, by autoradiography, whether a specific population of cells incorporate more 2DG during electrically active phase of the CR. The pattern of proteins synthesized by the eye from radioactive amino-acid precursors will be followed on 2-dimensional polyrylamide gels at different phases of the Cr. We will also use ionizing radiation, in conjunction with electrophysiological, morphological and biochemical, morphological and biochemical measurements, as a probe to localize the cells involved in the CR. Finally, we will etermine, by radioimmmunoassay, whether there are (cAMP) changes during cr and whether potent analogs of cAMP, effective on the neurosecretory bag cell neurons of Aplysia, can phase shift the CR.